The influence of basement block tectonics on ice thrust Wadena drift in the southern St. Croix moraine, Stearns Co, Minnesota
- St. Cloud State Univ., MN (United States)
Cretaceous mudstones containing horizontal bedding are found in the St. Croix moraine in southern Stearns County, Minnesota, These sediments are probably in-situ because they have been drilled to 14.5 m. and have horizontal bedding, based upon the orientation of concretions. The north end of this outcrop is truncated by a fault striking N90[degree]W and dipping north at 35 degrees. The orientation of concretions near the fault suggest normal fault displacement. A single water well log two miles northwest shows similar Cretaceous mudstones 70 m. lower. A significant aeromagnetic lineament striking N70[degree]W is located between the two sites and parallel to the orientation of the St. Croix moraine. Superior lobe ice may have depressed the northern block to produce a topographic barrier which stalled the ice and was at least partially responsible for the ice thrust glacial sediments located in the interior of the moraine. Deformed glacial sediments rest unconformably upon horizontal Cretaceous mudstones and consist of Wadena till, Superior till, perhaps an older pre-Wisconsinian till, glacial lacustrine sediments intercalated with till, wind-blown fine sand and outwash. After the northern basement block was depressed, a small normal fault developed in the Cretaceous sediments moving wind blown fine sand down. Older glacial materials were then ice-thrust onto this topographic high developed by ice loading. Structural features include at least 3 N90[degree]W, north-dipping thrust faults with materials tectonically transported from a depression located more than 3,000 feet to the north.
- OSTI ID:
- 6838100
- Report Number(s):
- CONF-9404217-; CODEN: GAAPBC
- Journal Information:
- Geological Society of America, Abstracts with Programs; (United States), Vol. 26:5; Conference: 27. annual conference of the North-Central Section of the Geological Society of America (GSA), Kalamazoo, MI (United States), 28-29 Apr 1994; ISSN 0016-7592
- Country of Publication:
- United States
- Language:
- English
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